This invention relates generally to ferrite devices, and more particularly, to a ferrite housing with inserts.
Ferrite devices, and in particular, ferrite circulators are typically configured as multi-port (e.g., three-port) passive RF or microwave devices having within a housing magnets and ferrite material that may be used to control the direction of signal flow in, for example, an RF circuit or a microwave circuit. For example, ferrite circulators may be used to control signal flow in wireless base station or power amplifier applications. Ferrite isolators also may be constructed by terminating one port of a ferrite circulator. Terminating one port results in signal or energy flow in only one direction, which may be used, for example, for isolating components in a chain of interconnected components.
The ferrite device (e.g., ferrite circulator or isolator) typically includes a magnetically biased ferrite disk or slab within a housing that is formed from a ferrous material. The housing for these ferrite devices is typically limited to ferrous materials because of the magnetic permeability requirement of the ferrite device. The housing for these ferrite devices can be metal injection molded, progressive die stamped or machined. The metal injection molded housing requires secondary machining and due to the thermal properties of the ferrous material (e.g., steel) used to form the housing, also requires adding or attaching a more thermally conductive material. These secondary operations add complexity, time and cost to the manufacturing process. The progressive die stamped housing has the same thermal issues as the metal injection molded housing and also requires a secondary machining process to finalize the shape of the housing as formed by the mold. Machining the housing from steel is costly and still requires a separate component or secondary process to address the thermal issues.
At least one known housing addresses these issues by manufacturing the housing from aluminum using a metal injection molded (MIM) process and then adds separate magnetic sections that surround the ferrite element within the housing. This process requires careful alignment of the magnetic sections in secondary operations, as well as finalizing the shape of the housing is secondary operations, which adds time and cost to the overall manufacturing process.
Moreover, the covers for these housings are also typically manufactured from a ferrous material. The covers often include a helical threaded portion that engages a mating portion on the housing. It is often difficult and costly to produce precise threading, particularly when a post plating process is required. Further, an additional steel disc is typically needed within the housing to enhance the magnetic return path in the ferrite assembly. This adds cost and complexity to the overall device.
Thus, known housings for ferrite devices require secondary operations that add complexity and cost to the overall device. The covers for these housings are also often difficult or costly to manufacture.